Can you please put the screenshot over here?
It might be the browser issue.
Try using the Mozilla Firefox latest version.
Well, everyone in my company is using IE11 and it works fine. And this user has been working on IE11 without issue.
Definitely it is not a user since you confirmed that this user is able to work on the another system. Neither FDM issue because it works correctly with the other machines having IE11.
So, what we left off? It is a specific user machine issue.
Now, heading with troubleshooting with user system issue.
a) Make sure user machine has followed all the guidelines of supported IE11 compatibility from Oracle, there may chances that user machine would have updated the IE11 resulting changes in the browser settings/reset or any windows updates which might change the configuration or settings.
Have below KM's review:
Hyperion Enterprise Performance Management (EPM) Products Support Status for Internet Explorer ( IE6, IE7, IE8, IE9, IE10 and IE11) (Doc ID 1355681.1)
Internet Explorer (IE7, IE8, IE9, IE10 and IE11) Recommended Settings for Oracle Hyperion Products (Doc ID 820892.1)
b) Acceptable that for all the other users are working find with IE11 but you have to agree that there is some changes in the user machine reason why it stopped working and based on circumstances you don't have to compare this system with other working system.
Having said, review this issue from the user machine perspective and try to find what was the last changes done before it was working fine, it will help you in further troubleshooting.